Reflecting element and projection system comprising the same

Abstract

A projection system includes a projector that emits imaging light, a polarization screen that selectively reflects, of the imaging light, only light in a specified state of polarization, and a reflecting element placed on an optical path between the projector and the polarization screen to reflect the imaging light. The projector emits imaging light containing circularly polarized light whose state of polarization varies according to the wave range of the light, and the first and the second reflective layers in the reflecting element have polarization characteristics and reflection wave ranges corresponding to the state of polarization and the wave range of the circularly polarized light contained in the imaging light in such a manner that the state of polarization of the circularly polarized light, after being reflected from the first and the second reflective layers, is uniform irrespective of the wave range of the light.

1. A projection system comprising:
 a projector that emits imaging light, 
 a polarization screen that selectively reflects, of the imaging light emitted from the projector, only light in a specified state of polarization to display an image, and 
 a reflecting element placed on an optical path between the projector and the polarization screen to reflect the imaging light, emitted from the projector and to project the same onto the polarization screen, the reflecting element comprising:
 a first reflective layer that selectively reflects only light in a specified wave range and transmits light in other wave ranges, and 
 a second reflective layer that reflects light in another wave range covering at least one wave range other than the specified wave range of the light reflected by the first reflective layer, 
 wherein either the first or the second reflective layer is a polarization-maintaining reflective layer that reflects circularly polarized light while maintaining the state of polarization of the circularly polarized light, and 
 the other reflective layer is a polarization-reversing reflective layer that reflects circularly polarized light while reversing the state of polarization of the circularly polarized light, 
 
 wherein the projector emits imaging light containing circularly polarized light whose state of polarization varies according to the wave range of the light, and 
 the first and the second reflective layers in the reflecting element have polarization characteristics and reflection wave ranges corresponding to the state of polarization and the wave range of the circularly polarized light contained in the imaging light emitted from the projector in such a manner that the state of polarization of the circularly polarized light, after being reflected from the first and the second reflective layers, is uniform irrespective of the wave range of the light. 
 
   
   
     2. The projection system according to  claim 1 , wherein the projector comprises a projector body that emits imaging light containing linearly polarized light whose state of polarization varies according to the wave range of the light, and a quarter wave plate that is placed on an optical path between the projector body and the reflecting element to convert the linearly polarized light contained in the imaging light emitted from the projector body into circularly polarized light. 
   
   
     3. The projection system according to  claim 2 , wherein the projector body is a liquid crystal projector. 
   
   
     4. The projection system according to  claim 1 , wherein the reflecting element is integrally incorporated in the projector. 
   
   
     5. The projection system according to  claim 1 , further comprising a reflector placed on an optical path between the reflecting element and the polarization screen to reflect the imaging light reflected from the reflecting element and to project the same onto the polarization screen. 
   
   
     6. A projection system comprising:
 a projector that emits imaging light, 
 a polarization screen that selectively reflects, of the imaging light emitted from the projector, only light in a specified state of polarization to display an image, and 
 a reflecting element placed on an optical path between the projector and the polarization screen to reflect the imaging light emitted from the projector and to project the same onto the polarization screen, the reflecting element comprising:
 a first reflective layer that selectively reflects only light in a specified wave range and transmits light in other wave ranges, 
 a second reflective layer that reflects light in another wave range covering at least one wave range other than the specified wave range of the light reflected by the first reflective layer, and 
 a quarter wavelength retardation layer that brings, to light incident on the first reflective layer, a phase shift equal to a quarter of the wavelength of the light, 
 wherein either the first or the second reflective layer is a polarization-maintaining reflective layer that reflects circularly polarized light while maintaining the state of polarization of the circularly polarized light, and 
 the other reflective layer is a polarization-reversing reflective layer that reflects circularly polarized light while reversing the state of polarization of the circularly polarized light, 
 
 wherein the projector emits imaging light containing linearly polarized light whose state of polarization varies according to the wave range of the light, 
 the quarter wavelength retardation layer in the reflecting element converts the linearly polarized light contained in the imaging light into circularly polarized light, and 
 the first and the second reflective layers in the reflecting element have polarization characteristics and reflection wave ranges corresponding to the state of polarization and the wave range of the circularly polarized light contained in the imaging light reflected by the reflecting element in such a manner that the state of polarization of the circularly polarized light, after being reflected from the first and the second reflective layers, is uniform irrespective of the wave range of the light. 
 
   
   
     7. The projection system according to  claim 6 , wherein the projector comprises a liquid crystal projector. 
   
   
     8. The projection system according to  claim 6 , wherein the reflecting element is integrally incorporated in the projector. 
   
   
     9. The projection system according to  claim 6 , further comprising a reflector placed on an optical path between the reflecting element and the polarization screen to reflect the imaging light reflected from the reflecting element and to project the same onto the polarization screen.